1. Field of the Invention
The present invention is directed to amplifiers and, more particularly, to amplifiers implemented with CMOS devices.
2. Related Art
Conventional amplifiers are implemented with bipolar transistor technologies, such as silicon germanium (SiGe), indium-Phosphide (InP), and other processes that offer high speed transistors. A bipolar amplifier is taught in Greshishchev, Y. M., and Schvan, P., “A 60 dB Dynamic Range 10 Gb/s Broadband SiGe HBT Limiting Amplifier,” 1999 IEEE International Solid-State Circuits Conference (ISSCC99), Session 22, Paper WP22.4, page 282-383, 0-7803-5126-6/99, incorporated herein by reference in its entirety.
A disadvantage of bipolar process technologies is their relatively high cost, which is generally due to the number of mask layers needed. Another disadvantage is that relatively few foundries exist to provide these process technologies to fabrication-less (“fab-less”) semiconductor companies. Digital CMOS processes are more suitable for the implementation of mixed analog/digital integrated circuit chips. So for the suitability of integration with the higher systems, CMOS processes are adopted more often than bi-polar processes. Yet another disadvantage of bipolar process technologies is the difficulty of integrating them with CMOS processes, which are nearly ubiquitous in the implementation of mixed analog/digital integrated circuit chips.
There is a need, therefore, for CMOS amplifiers, such as wideband CMOS gain stages.